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Date: Fri, 25 Jul 2014 13:16:39 -0700 From: Jesse Barnes <jbarnes@...tuousgeek.org> To: Joerg Roedel <joro@...tes.org> Cc: Andrew Morton <akpm@...ux-foundation.org>, Andrea Arcangeli <aarcange@...hat.com>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Rik van Riel <riel@...hat.com>, Hugh Dickins <hughd@...gle.com>, Mel Gorman <mgorman@...e.de>, Johannes Weiner <jweiner@...hat.com>, Jerome Glisse <jglisse@...hat.com>, jroedel@...e.de, Jay.Cornwall@....com, Oded.Gabbay@....com, John.Bridgman@....com, Suravee.Suthikulpanit@....com, ben.sander@....com, David Woodhouse <dwmw2@...radead.org>, linux-kernel@...r.kernel.org, linux-mm@...ck.org, iommu@...ts.linux-foundation.org Subject: Re: [PATCH 1/3] mmu_notifier: Add mmu_notifier_invalidate_range() On Thu, 24 Jul 2014 16:35:39 +0200 Joerg Roedel <joro@...tes.org> wrote: > From: Joerg Roedel <jroedel@...e.de> > > This notifier closes an important gap with the current > invalidate_range_start()/end() notifiers. The _start() part > is called when all pages are still mapped while the _end() > notifier is called when all pages are potentially unmapped > and already freed. > > This does not allow to manage external (non-CPU) hardware > TLBs with MMU-notifiers because there is no way to prevent > that hardware will establish new TLB entries between the > calls of these two functions. But this is a requirement to > the subsytem that implements these existing notifiers. > > To allow managing external TLBs the MMU-notifiers need to > catch the moment when pages are unmapped but not yet freed. > This new notifier catches that moment and notifies the > interested subsytem when pages that were unmapped are about > to be freed. The new notifier will only be called between > invalidate_range_start()/end(). So if we were actually sharing page tables, we should be able to make start/end no-ops and just use this new callback, assuming we didn't need to do any other serialization or debug stuff, right? Seems like a good addition, and saves us a bunch of trouble... Thanks, -- Jesse Barnes, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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